text:
Is the A-10 Warthog being discontinued?
Popular forum feedback on the A-10 Warthog is that it is held in high esteem however I also read that it is no longer being manufactured. Is this true and why would a highly successful combat aircraft be discontinued?

It hasn't been made for over 30 years, but it isn't being planned to be phased out of service until at least 2030, and by some estimates, 2040. If you read this somewhere, it would help to link the article, at this time there are no plans to retire the Warthog beyond its already expected service life. It may surprise you, but only 716 were made.

Thanks for your reply Ron.  My error - when reading the A-10 information, I did not consider the difference between ceasing manufacturer and retiring from service.

Is this true and why would a highly successful combat aircraft be discontinued? For the same reason that the F-14 was finally discontinued, and for the same reason that the F-4 was discontinued, and the same reason that the A-6 was discontinued. That broad question applies to any aircraft that is no longer in production.  Is your question about when the A-10 will no longer be used, or retired from service?  (It's still alive and well, despite numerous attempts to put it to bed ...)

My point being... why spend billions on designing/developing/manufacturing an alternate aircraft, like the F-35, that has lots of 'issues' to rectify prior to delivery.  Why not capitalise on an existing combat legend like the A-10 by redesigning/modernising/manufacturing a current version.  Constantly retrofitting an old aircraft is financial suicide.

Related: What does the term “white-scarf Air Force” mean?

A-10 entered service in 1976 and is the only production-built aircraft that has served in the USAF that was designed solely for close air support(CAS). With huge losses of A1 (226) in Vietnam war called for development for a aircraft capable for providing air support to ground troops and conduct counterinsurgency. If we look at the history of development of CAS it had direct competition from Army helicopter ( e.g AH-56 Cheyenne) for the above mentioned roles.
The CAS study provided two important recommendations for the Air Force: “(1) the Air Force should take steps to highlight in official USAF doctrine, tactics and procedures publications the methods for accomplishing those missions for which the armed helicopters were provided and which the Air Force considered part of the close air support function; and (2) to fulfill the requirements for the 1970 plus time period, the Air Force should take immediate and positive steps to obtain a specialized close air support aircraft, simpler and cheaper than the A-7, and with equal or better characteristics than the A-1.Based on Air Force and contractor studies, the estimated unit flyaway cost for the A-X was \$1 - \$1.2M (FY70)depending on purchase quantities. Research and Development costs were estimated at 240Million \$. Also for the projected unit cost (FY70)for the turboprop version was \$0.837M (600 aircraft buy) - \$0.937M (400 aircraft buy). The projected unit cost for the turbofan version was \$0.989M (600 aircraft buy) - \$1.092M (400 aircraft buy). Hence with the budget that airforce had they put up a order of 715 aircraft.

Production of the 715 A-10 aircraft finished in 1984. With A10 seeing most of action and noteworthy performance in Afghanistan and gulf wars by the turn of 1990s the aircraft was outdated in terms of avionics and more modern helicopters capable of performing same role (e.g Boeing AH-64 Apache). In 1992 air force purposed F-35 multi role fighter to replace A-10. To put numbers into perspective the U.S. Air Force stated that retirement of A-10 would save \$3.7 billion from 2015 to 2019.
With delay in F-35, air force retrofitted all A-10 and OA-10 aircraft in the fleet to the A-10C standard with a new flight computer, new glass cockpit displays and controls, two new 5.5-inch (140 mm) color displays with moving map function, and an integrated digital stores management system.
References:
https://web.archive.org/web/20150910033808/http://www.dtic.mil/dtic/tr/fulltext/u2/a530838.pdf
http://www.gao.gov/htext/d07415.html
http://www.airforcemag.com/MagazineArchive/Pages/2008/June%202008/0608fade.aspx
http://www.defenseindustrydaily.com/a-highertech-hog-the-a10c-pe-program-03187/
http://www.af.mil/AboutUs/FactSheets/Display/tabid/224/Article/104490/a-10-thunderbolt-ii.aspx

Interesting, but I'm not quite seeing how this is an answer to the questions raised?

Ceasing to manufacturer/ discontinuation of A-10, had its roots back to when A-X program was launched, as Army and airforce both wanted different programs (army prefered helicopters and air force wanted A-X). Due to constraint in budget 715 was ordered, never used till 1991 gulf war, by the time their capability was seen it was already old and F-35 was started in 1992 to replace it.

@Huntkil please consider expanding this in the answer by editing it, rather than in the comments.

You start a quote, “(1) the Air Force should... but don't indicate where the quote ends, so it's difficult to tell which part of that is "their" analysis and which part is yours. Also, you have some references which is great, but no indication of which reference that quote comes from, nor an indication of where your chart comes from.


text:
How fast do the F-35 weapons bay doors open/close during combat ops?

(YouTube)
I came across the following Norwegian F-35 video launching a live missile from its right bay door. Of course, opening the door and launching the missile drastically increases RCS, but it seemed to operate quite slowly, about 3-4 seconds for the whole operation.

My questions are:

Is combat-operation of the bay door really so slow or does it speed up for a lesser chance of detection by today's powerful A2A radars?
Is 3-4 seconds of an exposed RCS increasing surface tactically significant? Obviously, if it wasn't there would be no need to overly stress the components if unnecessary.

3-4 seconds may lead to a detection, but then again 1-2 seconds could too with a sophisticated radar system. The important thing is that 3-4 seconds is short enough that a detection would be extremely hard to exploit; by the time a missile could be launched the contact would have disappeared.
If by some chance a station managed to get a missile off in that short time-frame it would probably miss. There are 2 types of radar guided missiles:

Semi-Active radar homing: semi-active missiles only have a radar receiver, they home in on a target using radar painted by a ground station or airborne radar. If the targeting radar station loses lock then the missile will go wide
Active radar homing: active missiles have their own radar emitters which get switched on when they get close to their target, so they are no longer relying on the ground station which is much farther away. They still rely on the ground station to get close enough to use it though, so while active missiles have a better chance it's still very unlikely

So shaving a second off that time would give very little benefit. Having a door open longer would be bad though. In the book "Skunk Works" by Ben Rich and Leo Janos (former director of the Lockheed Skunk Works) Major Miles Pound wrote about his experiences in the first Iraq war flying an F117 when a bomb bay door got stuck open after dropping:

We came in at three in the morning using only eight airplanes and
  needing only two tankers to get us there and back, and took out three
  of the four nuclear reactors and heavily damaged the fourth. Once that
  first bomb hit all hell broke loose. I dropped my bombs, but I
  couldn’t get my bomb-bay door closed. That was as bad as it could get
  because a right angle is like a spotlight to ground radar and
  a bomb-bay door is a perfect right angle. And out of the corner of my
  eye I saw a missile firing up at me. I had one hand on the eject lever
  and the other trying to manually close that stalled bomb bay. As the
  missile closed on me, the door finally did, too, and I watched that
  missile curve harmlessly by me as it lost me in its homing. About an
  hour later I began breathing again.

"they home in on a target using radar painted by a ground station" That's not accurate. The target may also be painted by another aircraft or by the launching aircraft itself (which I believe is the most popular scenario).

@DeepSpace, it certainly can, but I am not sure it is most popular scenario—there is not that many fighters on patrol these days and they don't know where the stealth attackers will pop up, so surface-to-air is more likely than air-to-air.

Good point @DeepSpace, I've edited accordingly.

@DeepSpace for most angles when dealing with air-air encounters the doors would not be visible to the opposing aircraft. From the ground they're pretty much always visible.

The bomb bay doors were open long enough on F117A that the Serbs were able to shoot one down, so I wouldn't say that shaving a second off the open time is insignificant.

SAMs start out guided by ground based emitters and switch to internal radar close to the target.  We never initiated jamming/spoofing until the internal radar switched on.

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

sort: votes


text:
Why is this 737 MAX 8 still flying?
I just saw a plane overhead that was flying unusual low and it turns out it was a 737 MAX 8 that left from the Boeing factory in Renton.
https://fr24.com/BOE867/1fdcadbf
Are planes that are not yet operated by airlines exempt from being grounded?

Related, maybe a dupe?

Read the FAA Order in the duplicate question. Special permits and Experimental certificates are allowed for flight test.  Your linked flight was from Renton (737 production facility) to Moses Lake which Boeing uses for flight test.

It looks like the link is no longer active but in addition to Anilv's answer the EASA order also allows for ferry flight to have the aircraft fixed.

From the effective date and time of this AD, do not operate the
  aeroplane, except that a single non-commercial ferry flight (up to
  three flight cycles) may be accomplished to return the aeroplane to a
  location where the expected corrective action(s) can be accomplished.

Emergency order issued by the FAA allows for special flights including production flights testing, ferry etc.
The order is available on the FAA website.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
Why two passenger airplanes travel side by side?
Recently (2018-08-19 17:40 UTC) two planes flew above my city (Poznań, Poland). They were heading in the same direction, kept really close distance (side by side) - both flights to Riga:

https://www.flightradar24.com/data/flights/bt634
https://www.flightradar24.com/data/flights/bt684

Is this common? Why would they do that - are there any benefits of it?

Related if not duplicate: https://aviation.stackexchange.com/questions/36782/what-is-the-business-purpose-of-scheduling-two-separate-flights-on-the-very-same

Were they at the same altitude within, say, 300 hundred feet?

@Terry I'm not sure but they seemed pretty close on the altitude.

@Sanchises thanks. Well one of those flights was from Rome, the other one from Barcelona. Both the same airline.

Closely related, maybe a dupe?

Yep, Pondlife's suggestion is much more on the mark.

The top one is Baltic 634, the bottom one BT684.
As you can see they had 2000ft seperation. That's 600m for us europeans not accustomed to aviation.
Furthermore, at 17:40:19 BT634 reported in at 52.409599,16.981899. 17:40:25 BT684 reported in at 52.423222,17.019314. While those are 6 seconds apart, the planes were north-eastern course at the time, so I guesstimate that they had 1-2km horizontal seperation as well.
As to why - they're going the same place. The separation is big enough that there's almost certainly no benefit to it.

Just for context for the OP: minimum separation in RVSM airspace is just 1000ft, so 2000ft is plenty.

@Sanchises well, one could add at that point that if the separation would have been 1000ft, the two aircrafts would have been travelling in opposite directions

@vidarlo thanks for the thorough answer :)

Flights generally do not travel directly from origin to destination along the shortest (great circle) path; they do estimate that but then adjust it so the actual route filed passes over various airports and navaids along the way in a giant game of "connect the dots". There are only so many dots to connect, though, so the closer you get to a destination, the more likely any two planes' routes will converge--even though they started from completely different places.
It sounds like these two planes'' routes converged and by coincidence they just happened to get to that point at roughly the same time, but since they were at (or ATC moved them to) different altitudes, that's totally fine. Closer to their destination, ATC will start to give them slightly different turns to separate them properly for safe descent.


text:
What main landing gear actuator does the Boeing 777-300ER have?
I can't remember the name of this system was, but all I do know is that is a big actuator that only exists on the Boeing 777-300ER variant. It will pressurize the actuator according to the thrust input the cockpit. It will automatically tilt-up to get a better AOA.

The Boeing 777-300ER is the only variant of the 777, which has a Semi-Levered Gear. From the 777 FCOM (v2 14.20.3 Landing Gear - System Description):

Semi-Levered Gear
[777-300ER]
The semi-levered gear consists of an additional hydraulic actuator that connects the forward end of each main gear truck to the shock strut. During takeoff, the actuator locks to restrict rotation of the main gear truck and allow takeoff rotation about the aft wheel axle, thereby improving airplane performance capability. During landing, the actuator is unlocked to permit rotation of the main gear truck and provide additional damping.

The 777-300 and 777-300ER are both equally long at $ 73.86 \, \mathrm{m} $, which is about $ 10 \, \mathrm{m} $ longer than the -200 variants. Due to the higher risk of tailstrikes, both variants are equipped with a Tail Skid:

Tail Skid
[777-300 and 777-300ER]
The airplane is equipped with a tail skid system. The tail skid extends for takeoff and landing and retracts during flight. It helps protect the pressurized part of the airplane from contact with the runway. The tail skid uses the main lading gear actuation system.
The EICAS advisory message TAIL SKID is displayed when the tail skid is not in the correct position.

The -300ER however has a MTOW (maximum takeoff weight) of $ 352 \, \mathrm{t} $ compared to only $ 299 \, \mathrm{t} $ for the -300, which increases the risk of a tail strike during takeoff rotation.
This Boeing article explains it as follows:

The Boeing 777-300ER's new semi-levered landing gear system has performed flawlessly during the flight-test program. The unique gear, which is manufactured by Goodrich Corp., allows the airplane to rotate early by shifting the center of rotation from the main axle to aft axle of the three-axle landing gear truck. As the airplane rotates, the nose is allowed to rise higher earlier.

You can see the difference here:

(image source: airliners.net and youtube.com)

It's called a 'semi-levered landing gear'.
It does not tilt to increase Angle Of Attack (AOA) but rather it locks the main wheel bogey so the the airplane pivots around the rearmost axle during take-off instead of the middle of the bogey where it connects to the main landing gear strut.
The reason Boeing did this was to reduce the chance of a tail-strike. The 777-300ER has a semi-levered gear whereas the similar length 777-300 (non-ER) does not. Possibly the increased MTOW of the ER increased the possibility of tail-strike.


text:
Flight Training in US as an Alien
I am currently living in the UK, engaged to a US citizen and we are looking to marry and move to the US. The plan is to travel to US with a K1 Visa as fiancé, get married there and apply for adjustment of status. This would give me the right to live there, not work until work permit is issued.

Will I be able to start flight training with a flight school without work permit? Would I be able to apply for AFSP or would I need to wait for Adjustment of Status? Most flight schools seem to offer US Citizen or International Students option and I'm not sure which category I would fit in my situation.
Would I be able to obtain a FAA Medical with K1 Visa? Are these unrelated?

Related

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
How much unusable fuel is in the A320?
I was wondering how much unusable fuel is in each tank or maybe in total for an A320. I searched through the FCOM and could not find answers.
To add to this question is the fuel shown on the fuel SD page all usable fuel? Or is it unusable + usable fuel?
Please show the references to the answers.

You can find the amount of unusable fuel in the EASA Type Certificate Data Sheet. Here is an example table for the A320-200 from that document:

In general, the cockpit displays will always show the amount of usable fuel only. This is mandated e.g. by EASA CS 25.1337:

(b) Fuel quantity indicator. There must be means to indicate to the flight-crew members, the
  quantity, in litres, (gallons), or equivalent units, of usable fuel in each tank during flight. In
  addition –

Each fuel quantity indicator must be calibrated to read ‘zero’ during level flight when the
  quantity of fuel remaining in the tank is equal to the unusable fuel supply determined
  under CS 25.959;
Tanks with interconnected outlets and airspaces may be treated as one tank and need
  not have separate indicators; and
Each exposed sight gauge, used as a fuel quantity indicator, must be protected against
  damage.

(EASA Easy Access Rules for Large Aeroplanes)

That's an impressively small amount of unusable fuel as a fraction of the total!


text:
How to interpret BECMG and TEMPO in TAF?
I'm still confused on the change indicator BECMG. I am sure of the definition of TEMPO being only a temporary fluctuations in the time frame given, but will a TAF with a change of BECMG continue on with the changes in the BECMG or will it revert back to the general forecast in the beginning of the TAF (basically is it permanent change or is the change only applicable in the time frame given just like TEMPO). As it says that once a TEMPO is expected to be have fluctuations of more than 1 hour it will be classified as BECMG.
This is me quoting from WMO document 306, which is also  written in Annex 3 (1.3.3):

The change groups TTTTT YYGG/YeYeGeGe in the form of BECMG YYGG/YeYeGeGe shall indicate a change in forecast meteorological conditions expected to occur at either a regular or irregular rate at an unspecified time within the period YYGG to YeYeGeGe. The duration of the period YYGG to YeYeGeGe shall normally not exceed two hours and in any case shall not exceed four hours. The change groups shall be followed by a description of all the elements for which a change is forecast. When an element is not described in data groups which follow the change groups, the description of this element for the period between Y1Y1G1G1 and Y2Y2G2G2 shall be considered to remain valid subject to Regulation 51.1.5.
Note: The conditions described after the groups BECMG YYGG/YeYeGeGe are those expected to
  prevail from YeYeGeGe until Y2Y2G2G2, unless a further change is expected, in which case a further
  set of change groups BECMG YYGG/YeYeGeGe or FMYYGGgg must be used.
51.8.4 The change groups TTTTT YYGG/YeYeGeGe in the form of TEMPO YYGG/YeYeGeGe shall indicate frequent or infrequent temporary fluctuations in forecast meteorological
  conditions which are expected to last less than one hour in each instance and, in the aggregate cover, less than half of the period indicated by YYGG/YeYeGeGe.
Notes:

If the modified forecast condition is expected to last one hour or more, Regulation 51.8.2 or
  51.8.3 applies, i.e. the change groups BECMG YYGG/YeYeGeGe or FMYYGGgg must be used at the beginning and end of the period during which conditions are expected to depart from
  those forecast prior to YYGG or YYGGgg.
To keep forecasts clear and unambiguous, the use of change indicators should be carefully
  considered and kept to a minimum. In particular, the overlapping of change periods should be avoided. At any time during the period of validity of the TAF, only one possible variation in the prevailing forecast conditions should normally be indicated. The subdivision of the forecast period by FMYYGGgg should be used to avoid too complex forecasts in cases where many significant changes in weather conditions are expected to occur throughout the
  forecast period.

The BECMG group in a TAF describes a gradual change which will take place over a prolonged period of time, but will be the prevailing weather once that change is complete. The time period described in the TAF is the beginning and ending hour during which the gradual change is forecast to be in progress. At the end of the described time the change is expected to be complete and the forecast weather should be the prevailing weather thereafter.
See the description of BECMG from the US Aviation Weather site's TAF decoder page:

The BECMG group is used when a gradual change in conditions is expected over a longer time period, usually two hours. The time period when the change is expected is a four-digit group with the beginning hour and ending hour of the change period which follows the BECMG indicator. The gradual change will occur at an unspecified time within this time period. Only the conditions are carried over from the previous time group.

Conversely, with the TEMPO group, the described time period is a beginning and ending period after which the weather is forecast revert to the previously prevailing weather.
See the description of TEMPO from the US Aviation Weather site's TAF decoder page:

The TEMPO group is used for any conditions in wind, visibility, weather, or sky condition which are expected to last for generally less than an hour at a time (occasional), and are expected to occur during less than half the time period. The TEMPO indicator is followed by a four-digit group giving the beginning hour and ending hour of the time period during which the temporary conditions are expected. Only the changing forecast meteorological conditions are included in TEMPO groups. The omitted conditions are carried over from the previous time group.

TEMPO is a temporary fluctuations in the time frame given, the fluctuations should be not more than an hour in each instant and in aggregate it should be not more than half of the forecasting period. TEMPO will revert back when the forecasting period is over.
BECMG is the permanent change, the process of gradual change is not more than two hours and should not exceed four hours.

In plain words- Becoming means that once the change occurs, you can now relate to the changes noted in the Becoming report as prevailing.
More closely- you regard every improvement occurring as it occurred the end of the time of the becoming period, and deteriorating as occurring right at the beginning of the window.
Every aspect of weather that was not noted in the report- shall be regarded as the previous prevailing report.
So, if in the Becoming report we had- BECMG 220/15- only the wind changed, but the cloud coverage stays the same as before.
The change is permanent.
I am attaching a link to the Jeppsen guide here- Jeppsen general link.


text:
Can a Eurofighter 2000 trainer be converted to a combat-capable Eurofighter 2000?
It surprises me to see that in some aircraft inventory listings, a rather considerable percentage of combat aircraft are "trainer" versions. E.g., the current inventory of the Spanish Air Force.
For Spain, it is claimed they have 56 Eurofighter 2000, and 12 trainers. Somewhat similar numbers apply to their F-18 variants regarding combat aircraft and trainer aircraft.
I'm curious what the difference is between these Eurofighter 2000 combat vs. trainer aircraft. In particular, how much effort is it to make a trainer EF2000 combat ready? Perhaps they actually are combat ready? Surely there are some differences though, such as having two seats? What else?

Normally, the second pilot is accommodated by removing or reducing a fuel tank. The two-seater will have the same equipment (how else should it be used for training?) but will have less range and endurance.

From the Wikipedia page on the Eurofighter Typhoon, under Variants:

The Eurofighter is produced in single-seat and twin-seat variants. The twin-seat variant is not used operationally, but only for training, though it is combat capable.

No source is cited for that claim, but it seems logical enough.

It makes perfect sense for a Trainer variant to be equally combat ready as the single seat variant, think of weapons training.

@DohnJoe Doesn't it also make sense in the context of war? If you only have 56 aircraft, and 12 trainers, wouldn't you want the 12 trainers to also be combat capable, albeit with a slight disadvantage due to having less fuel capacity?

@AlphaCentauri: Especially since, if you're being invaded and need all the planes you can get, lower fuel capacity and the resultant shorter range don't matter (since you're over friendly territory and can land and refuel basically wherever and/or whenever you want and/or need to).

It seems to me that it is important to note that the Typhoon 'trainer' aircraft are more accurately referred to as "advanced trainers", i.e. they are used for type-conversion, not for actually teaching pilots to fly. For the kind of plane used for basic training, there is very little need for combat-readiness.


text:
Why are special aircraft used for the carriers in the United States Navy?
Why are aircraft such as the legacy F-14 and now the F/A-18 used by the US Navy carriers?
It seems to me that developing a new aircraft from the ground up is very expensive. Is it not possible to have converted F-16 or F-15's for carrier operations? Obvious modifications such as folding wings, stronger undercarriage, hook, etc. I'm sure there are many more I'm not aware of.
Is the reason that these aircraft (F-16, F-15) are not suitable for carrier operations, even with modifications?
Isn't this what the Russian Navy did with their fighters? The carrier versions of the MiG-29 and Su-27?
What are the reasons the US employs unique carrier aircraft? Is the reason political? Technical?

The Navy prefers twin engine aircraft, so the F-16 is out, but Vought developed the idea as the Vought 1600. The F-15 was also explored as the F-15N "Sea Eagle". Ultimately the F-15N-PHX was too heavy to be a carrier operations aircraft. By that time the F-14 was much better suited to carrier ops and was selected over the problems with the F-15N.

If you think those aircraft are expensive, check out the price tag on the F-35.

The first thing to do when examining apparent inconsistencies in US defence procurement is to look at which companies (and hence states) have secured the contracts. Most fighter jets require additional compartments to fit in all of the pork barrels.

This also raises the question why they don't just take the carrier-based aircraft and use the same things for the land-based forces? Surely if an aircraft can land on a carrier, it can also land on an airstrip. Is it because without the hardware required to land on a carrier, an aircraft could carry more weapons and ammunition?

It was made a temptative also with the naval version of the F-22, dropped before first prototype...

It's technical, not political
The F-35 was an attempt to do exactly what you propose, lowering costs by planned sharing of 80% of parts across variants, but it turns out that the USN's F-35C costs over twice as much as the USAF's F-35A, and only shares 20-25% of it's parts. The project has been a disaster practically since day one, and the services are already working on separate replacements tailored from the start for their very different missions.
Per Wikipedia, the USN decided a carrier variant of the F-15 would be too expensive and the YF-16 was inherently not suitable for carriers, so they modified the YF-17 into the F/A-18 by making the changes you propose. The USAF didn't need those changes, so they stuck with the faster and cheaper YF-16, which became the F-16.
Keep in mind that all US aircraft carriers combined hold the fourth largest air force in the world. That sort of volume means the USN can afford to customize planes for their exact needs, whereas other countries with far smaller carrier fleets may be forced to make do with planes that the USN considers "unsuitable" or "too expensive", especially if they aren't US allies.

Comments are not for extended discussion; this conversation has been moved to chat.

The YF-17 is the answer to your question. It is the predecessor to the F/A-18, and was designed as a land-based fighter. The YF-17 is much lighter than the F/A-18, because it does not need to carry equipment for carrier landings. Adding this equipment makes the aircraft heavier, compromising performance. You then need to compensate for the added weight, but the airframe may not have space for different engines or additional fuel.
Overall there are just so many changes to be made, that as StephenS points out with the F-35, you don't end up saving money by having a few things in common.
There is a saying: "Jack of all trades, master of none." That is, if you design something to be useful in all situations, it will not excel at any of them.
The F-4 Phantom did do the reverse, starting as a Naval aircraft before later also being adopted by the USAF and USMC.

Yeah, I think the simple answer is really just "They tried it and found it doesn't work."

Like the F-4, lot of countries without carriers use carrier-optimized fighters. Canada uses F/A-18 fighters, because the two engines make it safer to get back from sea patrols. Iran uses F-14 Tomcats because they can't buy newer stuff due to embargo. Neither of these operate or plan to operate CVs. Switzerland is even landlocked (with a handful of F/A-18s)!

https://www.globalsecurity.org/military/world/europe/ch-luftwaffe-fa-18.htm

The needs to operate on a carrier are different than the needs for a land based aircraft. They are subtle, but significant. As others have pointed out, the F-35 attempted to address these issues and wound up way over budget. (It was made even more complicated by the addition of a STOVL version for the Marines, the F-35B).
CATOBAR aircraft differ from conventional aircraft in subtle, but very important ways. Takeoff and landing on a carrier is significantly different. Its landing gear must be significantly strengthened to handle the "controlled crash" of landing on a carrier deck, and the sharp deceleration of the arresting cable, and the sharp acceleration of the catapult when taking off. It needs a strong arresting hook to snag the cables on landing. The engines can't melt the carrier deck or blast shields on takeoff.
The short flight deck and tricky approach requires a lower landing speed, and better low speed handling requiring a significantly larger wing area. This also gives more lift to keep the same cruising range despite all that extra weight.
The limited space on a carrier often requires folding wings, the joints must be able to handle all the stresses of combat maneuvering. More weight and more complexity.
The aircraft must be able to be maintained and repaired while at sea with the stores and equipment available to a carrier. It must be resistant to salt water, particularly hard if you're using advanced skins to reduce radar cross-section. The limited storage space means it ideally has to share the same fuel and weapons and other consumables with other carrier aircraft.
Finally there are self-inflicted inter-service incompatibilities. The US Navy and Air Force use different aerial refueling systems requiring different parts and plumbing.

Most navies look at all these extra requirements (and weight, always weight) and are satisfied with lower performance, usually lower takeoff and landing weights meaning less fuel and less stores. For example, ski-jumps like on the Admiral Kuznetsov are simpler and cheaper than catapults and reduce the strain on the aircraft making conversion to naval simpler, but they limit the takeoff speed and weight of the aircraft. Better to have some sort of fixed-wing air capability within their budget than none.
The US Navy doesn't have any of that. They want a naval aircraft that is the equal or better than land based aircraft. That comes at a cost in weight, money, and complexity.

Generally spot on, but the USN/USMC aerial refueling, probe-and-drogue, is the system used by most of the world's air forces, including Russia, China, NATO,  USAF and USA helicopters. The flying-boom USAF system is only used by USAF, Australia, the Netherlands, Israel, Turkey, and Iran.

@K7AAY Oop, you are correct.

Another significant difference is the use of twin engines for redundancy. Over land, you can do an engine-out emergency landing or bail out in case of an engine failure, both of which are close to a death sentence out at sea.

Another reason that carrier aircraft tend to be quite different from land based aircraft is the environment in which they operate: lots of salt. Consequently, carrier aircraft contain a much greater degree of corrosion resistant components, raising the price and in some cases the weight.
Several naval aircraft have been adopted by land air forces. The USAF and several other air forces adopted the F4 Phantom. USAF also used the A1 Skyraider. Several land based air forces have used the US A4 Skyhawk and F18 Hornet in a land based role. The Hawker Sea Fury was used by Iraq in the 1950's and 1960's. The Philippines operated F8 Crusaders as land based aircraft in the 1980's.
Land based aircraft designs have been adopted for carrier use, albeit with major changes. The Supermarine Seafire was a conversion of the Spifire. In the US, the F86 Sabre was produced in a naval variant, the FJ2/3/4 Fury. The Russian MIG29 has been produced in a naval variant for operation on their carrier. The previously mentioned Hawker Sea Fury was an adaptation of the Hawker Tempest land based fighter.
Plus a couple of desperation measures: The Hawker Hurricane was used at sea on the CAM merchant ships to defend against FW200 Kondor aircraft, but that was a one time use only with no ability to land at sea, and the pilot was often lost in the frigid North Atlantic waters. Plus the one time use of B25 bombers from the USS Hornet.

The reasons are several: one major one is that naval aircraft require reinforced undercarriages and airframes in order to land safely. When you land on a carrier, you are coming in on a very short runway, and need to stop quickly.
To do this, a landing arrest cable is needed (in the case of most modern carries, they have 4). But it is incredibly easy to miss those or get a "spitting" one (when it for whatever reason pops off the hook), so when you come in you have to increase thrust to full (throttle up) so that if you miss you can take off again and come back around.
If you try landing like that with an F-16, you'll rip the entire undercarriage of your plane right out. So all that has to be built heavier and reinforced, with landing gear struts, tires and whatnot that can handle it.
Also: those folding/ variable geometry wings require more onboard mechanisms to take the brunt of the workload, and more maintenance to keep functioning. That means easy accessibility and reliability under less than ideal conditions.
You also have specialized functions as well: the F-14 is a fleet interceptor, while the F/A 18 is attack. Each of these require specific parameters and whatnot (although the newer "Super Hornet" fills the draft nicely).
On that note, Russia did do this but there are reasons you don't see them use that extensively. The modifications needed to make them shipworthy increase their costs even more than to simply build a purpose-built craft for the role.
You have to understand that nature of naval aviation and the tolls that the sea environment takes on planes to begin with, let alone the rigors that carrier duty imposes. A plane built for normal flight duty will fall apart if you try to use it on a carrier unmodified.
It simply cannot take the strain and stress, they're just not built for it. If you want to see what kind of failures happen when you try to use one for both Project VFX, which led to the F-14 Tomcat, demonstrated it.


text:
What capabilities have been lost with the retirement of the F-14?
As in the title. Ideally, I am looking for a study in the public domain that would summarize the US Navy's loss of capabilities with the disappearance of the Grumman F-14 Tomcat. I will also accept an answer that gives a justified list. Obviously, there's the AIM-54 Phoenix, of which the Tomcat could carry... six? There's also the performance of the F-14, top speed, though I am unsure how relevant this is.
As a bonus, had the F-14 still been around in significant numbers, would a Super Tomcat be all but inevitable? Not looking for guesses here. If someone can point to budget plans in the works or similar that would indicate that, yes, if the F-14 had not been retired, the Super Tomcat would have been a reality.

If Tomcat has a successor then so must Phoenix, which IMO should have happened but didn't. An AIM-120 shot from the cat really isn't that much different from one shot from the bug.

The F-14 wasn't just an air defense fighter. Any multirole would work for a carrier-on-carrier fight, winning through numbers and training. The F-14 was designed to counter a specific threat: Tu-16s and later Tu-22Ms armed with long-range anti-ship missiles. The Soviets had dedicated an entire branch of the military to countering USN ships with aircraft and air-launched missiles.
Only the F-111B could patrol far enough out, intercept fast enough, and carry sufficiently long-ranged weapons to engage these bombers before they could release their payload. The technology of the 1960s (or even the 1970s-1990s) wasn't capable of intercepting such missiles once released.
The F-111 Aardvark had even more problems than the F-14A. It was too heavy, difficult to handle, and could barely fit on or operate from a carrier. Adopting the Tomcat was by far the lesser of three evils. The third, least desirable option would be to keep out of range of land-based aircraft. More on the F-14's design compromises in this question.
With the Tomcat's phase-out and retirement in the late 1990s-2000s, the USN has lost the capability to intercept missile-armed bombers at standoff range on its own. This capability has since been replaced by:

Ending the Cold War. At the time, it was believed the threat wouldn't be relevant for many decades. The rise of China had perhaps been underestimated.
Diplomatic treaties. START, SALT II, and CTR have targeted the Tu-22M for capability reduction, dismantling, and export restrictions. Only 66 out of the original 500 can fly today.
Improved AEW radars on the E-2D, increased E-3 coverage through allies, and more spy satellites give earlier warning against an incoming strike, giving slower fighters time to intercept.
The SM-3 and SM-6 missiles, which have anti-ballistic capabilities, and could intercept some, though not all, incoming anti-ship missiles.
The Meteor and to a lesser extent the AIM-120D approach the AIM-54's range, and their better guidance should compensate for smaller warheads.
Electronics export restrictions are being reintroduced, to slow down a re-emergence of the threat on the same comparative level that it was pre-1991.

While no one point is a complete replacement, they work together. Better avionics, improved C5I, more NATO-stationed forces can compensate for the loss of dedicated capabilities. The threat itself has also diminished greatly; it will be a while before China can catch up to the late Soviet capability level.
The Super Tomcat was an industry proposal. The Navy didn't ask for it by name; they weren't happy with the original. Even the boldest proposals still point at a maintenance-intensive, non-stealth aircraft, with a moderate air-to-ground payload compared to its weight.
The F-14 was indispensable against the Tu-22M, while also being a good general purpose interceptor. Swing wings aren't needed for simple bombing runs. At the same time, it's likely to be inadequate against the J-20, H-20, or a possible new J-20 or PAK FA/DA/etc derived naval strike bomber. These stealth aircraft can be countered by getting close through better stealth, where the US still has a lead, wide-cast UAV nets, SIGINT, and/or intercepting their payload with even better missiles.
Had the Tomcat still been around, it would've been modernized to some E, F or G variant. It's not likely that the USN would've chosen to spend more on it than necessary. Update the avionics to work with modern munitions, put in more glass, use a curved windscreen and a regular HUD so the pilot can see in front of them. The Super Hornet is 40% larger than the original; there's no room to enlarge the Tomcat, itself designed to only-just-fit on a carrier.
So a Super Tomcat wouldn't be inevitable. Even in absence of the Hornet, the Navy would remain very keen to get a further improved, faster, longer-ranged F-35C. They could even support a naval F-22, had the recent political escalations happened while the Raptor was still in production. Stealth has become the new speed, though it's still only one capability.

P.S.
While it's only a simulation, the sim group Grim Reapers has run through some scenarios of such a strike, and a full complement of F-14's came the closest to saving the carrier. Similar results have been replicated in Command: Modern Operations, and no doubt many times before by actual military researchers, prompting the Tomcat's development and then retirement. Per this simulation, the remaining Tu-22M fleet is only enough to take down one CSG. Even though the missiles have improved, the bombers haven't changed much.

This is an excellent answer, enjoyable read. I do seem to recall that the Navy considered the YF-23, or am I mistaken?

@AlphaCentauri Sorry for the delay, original reply didn't get sent. The USN did consider the YF-23, but there wasn't enough budget for two stealth fighters. The USAF picked the YF-22, and a naval version was requested, but didn't get accepted.

Important to note that China had not emphasize its H6--K bomber fleet, able to strike with antiship cruise missiles, preferring to develop land-based balistic anti ship missiles (DF-21) because they thought they would be more difficult to intercept by, of course, aircrafts, but also by anti-air missiles

The
Range, speed and Radar size profile. Thou tomcat was a notorious hanger queen, The arrival of F18 Super Hornet and the AMRAAM missile sealed its fate. F14's Phoenix was extremely costly to service and had poor track record, except Iran where it performed... but little reliable data except reports on Iran Air force use.


text:
What problems would the early F-16 have if they were to fight during night?
From Wikipedia:

Designed as an air superiority day fighter, it evolved into a successful all-weather multirole aircraft.

There is no citation for this, so I suppose first asking if this is even true should be the first order of business. However, my real questions are the following.

Assuming the quote above is true, what difficulties would early F-16s (F-16A?) have with night operations when encountering enemy aircraft?
What is it with modern F-16s that make them better suited for engaging enemy aircraft during the night? Obviously I know they have more modern avionics, but specifically, what is the difference in this night fighting context?

When the LWF program began, its founders envisioned an aircraft purebred to engage the Soviet threat with machines which more closely matched the majority of Soviet fighters at that time ie lightweight, very maneuverable day fighters ie equipped with minimal avionics, a cannon(s) and short range IR guided missiles.  Pierre Sprey had envisioned an even smaller fighter when he didn’t even have a fire control radar in it, but it was not developed past his proposal.
The prototype and development F-16s were a far cry from a modern Block 60+ F-16 is today in terms of avionics and capabilities, but the first service F-16, the Block 15 F-16A/B, had good day and night air-to-air capabilities with the APG-66 radars.  They were however limited to good weather air-to-ground operations as they were limited in their precision munitions delivery capability.
Upgrades over the next three decades of service led to the current incarnations of the Viper equipped with helmet mounted cueing systems, advanced fire control AESA radar sets, IR night and precision weapons targeting systems, BVR TARH capable air to air missiles, advanced glass cockpit displays, etc.  It must also be noted that, while these system offer addition capabilities, the added weight and complexity diminishes aircraft performance in traditional fighter metrics as well.  Nevertheless the F-16 still remains a fine fighter regardless.
The capability vs cost vs performance debate is always controversial and does not show any signs of ending soon, though the military seems to prefer the most advanced and capable hardware it can buy at the expense of operating costs and reliability.  This has been made painfully clear with the F-35 program.

The main disadvantages of night operations are that the pilot can't see targets and threats as well, and that the background is cooler, so the aircraft has a more easily detectable infrared signature. This is true of all aircraft, but over time avionics have improved that mitigate the limitations of the pilot's vision. The IR signature is dealt with by trying to kill the enemy from very far away--to be able to see them before they see you. Range of detection systems has increased over time.
Here are some examples from the Wikipedia article:

The MLU introduced compatibility with night-vision goggles (NVG). The
  Boeing Joint Helmet Mounted Cueing System (JHMCS) is available from
  Block 40 onwards, for targeting based on where the pilot's head faces,
  unrestricted by the HUD, using high-off-boresight missiles like the AIM-9X.[88]

...

The F-16A/B was originally equipped with the Westinghouse AN/APG-66
  fire-control radar. Its slotted planar array antenna was designed to
  be compact to fit into the F-16's relatively small nose. In uplook
  mode, the APG-66 uses a low pulse-repetition frequency (PRF) for
  medium- and high-altitude target detection in a low-clutter
  environment, and in look-down/shoot-down employs a medium PRF for
  heavy clutter environments. It has four operating frequencies within
  the X band, and provides four air-to-air and seven air-to-ground
  operating modes for combat, even at night or in bad weather. The Block
  15's APG-66(V)2 model added a more powerful signal processing, higher
  output power, improved reliability and increased range in cluttered or
  jamming environments. The Mid-Life Update (MLU) program introduced a
  new model, APG-66(V)2A, which features higher speed and more
  memory.[89]

...

The Block 40/42's APG-68(V)1 model added full compatibility with
  Lockheed Martin Low-Altitude Navigation and Targeting Infra-Red for
  Night (LANTIRN) pods, and a high-PRF pulse-Doppler track mode to
  provide continuous-wave radar (CW) target illumination for semi-active
  radar-homing (SARH) missiles like the AIM-7 Sparrow. Block 50/52 F-16s
  initially used the more reliable APG-68(V)5 which has a programmable
  signal processor employing Very-High-Speed Integrated Circuit (VHSIC)
  technology. The Advanced Block 50/52 (or 50+/52+) are equipped with
  the APG-68(V)9 radar, with a 30% greater air-to-air detection range
  and a synthetic aperture radar (SAR) mode for high-resolution mapping
  and target detection-recognition. In August 2004, Northrop Grumman
  were contracted to upgrade the APG-68 radars of Block 40/42/50/52
  aircraft to the (V)10 standard, providing all-weather autonomous
  detection and targeting for Global Positioning System (GPS)-aided
  precision weapons, SAR mapping and terrain-following radar (TF) modes,
  as well as interleaving of all modes.[42]

"...the background is cooler, so the aircraft has a more easily detectable infrared signature": given the jet exhaust temperature, I doubt that day/night would make a difference. You have any source for that assertion ?

Check out figure 10 of this paper: https://www.researchgate.net/publication/258494738_Infrared_Signature_Modeling_and_Analysis_of_Aircraft_Plume
Almost all of the radiation emitted by the aircraft is absorbed by the atmosphere. In the bands where the radiation passes, the sun also emits strongly in those bands (the sun is hotter than a jet exhaust, after all). When the sun's radiation in these bands gets reflected by the earth or scattered by the atmosphere, or when the target is near the sun in the detector's field of view, the difference in contrast between night and day can be huge.

Thanks! Surprising, indeed.


text:
Why did older versions of B747 use radioactive material?
What was its purpose and in which part of the aircraft was it being used?

Depleted uranium was used as counterweights at the aileron balance panels; the outboard elevator and the upper rudder. Counterweights are used for maintaining the center of gravity(CG).
The process of maintaining CG falls under weight and balance. All proceedings and measures are found in the type certificate data sheet(TCDS) and it also includes the maximum certificate take off weight(MCTOW)
The CG must be always situated forward of the center of pressure(COP)
"You might have seen the flight crew moving person(s) from their seats to another seat after each stop overs" That is a part of the weight and balance procedure.
The idea behind this procedure is to NOT make the nose heavy as just condition will require additional runway distance during T/O and also increase the stall speed while a Tail heavy condition will make it harder to level the flight after T/O and would cause a wing stalling.
Stall speed is the minimum velocity at which the wings can begin to produce lift
Wing stall occurs when the transition point A.K.A boundary layer  moves forward towards the leading edge of the wing during a high rate of climb and/or when the boundary layer is shortened. Transitional point is a point on the wings upper chamber at which the laminar flow of the relative wind breaks and changes to turbulent flow and its effect reduces lift
So what was the reason?
Uranium was ideal because of its high density property such as a small volume unit can have a greater amount of mass and occupy less space yet still provide the needed weight to counter balance the aircraft
This depleted uranium was cladded with nickel and cadmium and painted with a primer and a topcoat. However, the risk of human exposure to this radioactive material was extremely high especially in the maintenance side of things.  Therefore, changes were being made with the introduction of Tungsten.
Cladding is a procedure that involves coating a metal with a thin layer of another metal. Either to minimise corrosion or with bearings you would do this procedure to harden its surface while keeping its core ductile/and or soft

Comments have been moved to chat; please do not continue the discussion here. Before posting a comment below this one, please review the purposes of comments. Comments that do not request clarification or suggest improvements usually belong as an answer, on [meta], or in [chat]. Comments continuing discussion may be removed.

The counterweights were 12 to 83lbs, 99% depleted uranium, coated with nickel and cadmium. There were "21 to 31" of the weights in the tail, with 692-1059 pounds of counterweights per plane. It was used on planes from 1968-1981, Boeing estimates about 300 tons in use (or as spares).
They switched to tungsten counterweights after that.
Boeing noted the location in the tail meant the depleted uranium was 25 feet from the back of the passenger cabin, and about the same distance to ground personnel.
simpleflying says there were six weights in (each) elevator and eight in the rudder.
sources: 1994 letter from Boeing to Oak Ridge National Laboratory (pdf), simpleflying.

Comments have been moved to chat; please do not continue the discussion here. Before posting a comment below this one, please review the purposes of comments. Comments that do not request clarification or suggest improvements usually belong as an answer, on [meta], or in [chat]. Comments continuing discussion may be removed.


text:
How does rudder braking work?
I've always been unable to understand how rudder braking/toe braking works and how you steer while using rudder braking. Hence I came to this website with possibly the most knowledgeable people I could find. So far I have come to believe you must step on both rudder pedals to used rudder braking, but I find it hard to understand as how must one steer otherwise?
Do I have the whole concept of rudder braking wrong or is there something I may be missing?

Related question mentions: "To operate the rudder you press on the bottom part of the pedals, so that they slide back and forth on tracks, and to operate the brakes, you press the top part of the pedals so that they rotate towards the floor."

Where did you hear the term "rudder braking"?  Because i think your answer is in the other question...

@Micheal Hall, yes indeed that does help!

I've always heard "rudder brakes" called toe brakes, but I think I understand what you mean.
When you're operating the brakes, you're rotating the pedals about their centers using your ankles (similar to the gas pedal of a car). When you're operating the rudder, you're sliding the pedals backwards and forwards, using your whole leg. You combine the two inputs to provide steering and braking.

That was really helpful! Appreciate it!

In addition to the answers and comments that clarify the potential confusion between 'normal' rudder controls and wheel braking with rudder toe-brakes, I thought it might be interesting to add that at least one general aviation plane is being designed with actual rudder braking.
The DarkAero 1 is unusual in that it has a split rudder that is designed to be able to open out in a way to provide air brakes.  Presumably it won't be much use when taxiing, but I suspect that in addition to being useful on approach to landing, could also be useful on the ground when coming to a stop after landing.  It might save a bit of wear on the brake pads if nothing else.
There's a video explaining it here:

Edit:
Re-reading your initial question and the (currently) only other answer, I feel that your question has not really been answered.
With regards to steering the aircraft on the ground, there are a number of methods, but they aren't all necessarily available on all aircraft or effective at all times.
You can steer using the rudder, but only if there is sufficient airflow across it (ie you are going fast enough) for a sufficient amount of lift to be generated.
Planes equipped with differential toe-brakes (each brake can be operated in isolation to the other) can apply braking to a single wheel which will cause the plane to turn.
Planes equipped with rudder steering (as well as operating the rudder, the pedals are connected to the nosewheel) can utilise this.
My own plane has toe brakes, but not nosewheel steering.  I find that on initial acceleration for take off when the rudder is ineffective, I have no choice but to apply brakes to counter the rotational forces of the engine/propeller wash.  Applying brakes on take off is not ideal, especially when your plane needs to use most of the runway!


text:
What is the correct term for the type of performance chart where curved lines are followed?
What is the correct term for the type of performance chart where, from a starting location, curved lines are followed to various reference points to eventually find a solution?
For a specific example, the type of chart I'm asking about can be found in the Pilot's Handbook of Aeronautical Knowledge as Figure 11-23:

Background to the question: I would like to reverse-engineer a performance chart in order to use it in a spreadsheet. I have no idea how to do this but if I can discover the name of the type of chart it is, I can begin by looking for notes from other people who have attempted the same.

Since I do not have this Pilot's Handbook of Aeronautical Knowledge, I'm left wondering what you want. Could it be a chart like this one?

While both answers below are good, neither answers the question “what is the correct term for this type of chart.”  But, could it be that there is a cleaner way to accomplish your goal than reverse engineering a paper chart into a spreadsheet?  Maybe if you more completely shared your problem/vision with us someone can suggest the best option?  (Along the lines of what has already been put forth...)

@MichaelHall - I agree that both answers are good and also that neither actually answers my question, but I think I am to blame rather than the answerers.  It may turn out that performance charts don't have a particular name other than "performance charts".  I may edit the question to bring it more in line with the answers that have already been provided.

I believe the term you are looking for is nomograph.

The correct term is nomograph or nomogram. Thanks Gerry!
Also, thank you to Peter Kämpf and Dean F. for helping to answer my actual question, instead of the one I asked.

After reviewing your profile, I assume you already know what these charts are, how to use them, and for what they are used. If you are trying to derive a spreadsheet for the data, you may want to take a look at TakeOff and Landing Distance tables for similar models. Alternatively, you could derive a program to handle each set of data in each section of the chart separately.
In other words, design a program to:

Calculate the pressure altitude based on known field elevations and barometric pressures/altimeter readings in the Kollsman window.
Calculate the density altitude based on known pressure altitudes and temperatures.
Calculate the ground roll distance of an aircraft based on known density altitudes and aircraft takeoff weights at given lift-off speeds.
Calculate the ground roll distance adjustment based on known headwind/tailwind components.
Calculate total distance required to clear an obstacle based on known adjusted ground roll distances and obstacle heights.
Add an adjustment factor for aircraft, weather, runway, and other conditions as well as experience, skill, ability and other pilot factors.

You will probably have to pre-calculate several data points at each stage, then interpolate the rest. For more exact plotting of data points, you will have to know the logarithmic or exponential algorithm used to calculate the curve in each step. Or, was each step drawn from observed data. Try Googling deriving logarithms.
Programs like ForeFlight has done this for several aircraft models.

I have done this before. It was a combination of FORTRAN for the numbers and Tcl/Tk for the plotting. How did it work?
First, you need a trim routine which computes the forces in all three axes and interprets the remainder as an acceleration. This requires an aerodynamic model and an engine model which could be represented by tables or discrete equations, as you like. Now you will have values which feed an integration where the conditions are updated for small time steps. Rinse and repeat with a time step of 0.5 to 2 seconds.
At some point the ground speed has reached v$_{rot}$ and your numeric model has to add negative elevator deflection to lift the nose. I used a standard pitch rate of 5° per second, but maybe you want to use less. Here the time step should be reduced for improved accuracy. If lift exceeds weight, the aircraft lifts off the runway and you have the distance and time for the ground run. Now the aircraft flies and climb rate needs to be chosen such that the aircraft arrives at the obstacle height at both 1.3 times v$_{Stall}$ and the obstacle height (might be 35 or 50 ft, depending on takeoff rules). Here you get the values for the full takeoff-length and time.
How would you get the climb rate right? I simply compared the projected time until obstacle height is reached and until 1.3 times v$_{Stall}$ is reached and adjusted the flight path angle such that both became equal.
Now you need to vary all the parameters of interest and repeat the calculation for variations in:

ambient temperature
take-off mass
flap setting
runway inclination
wind

and whatever else comes to mind. For a landing chart you reverse the sequence but the approach is pretty much the same.


text:
What is a good and simple software for calculating propeller thrust and required power?
My main requirements:

Calculate propeller thrust with big range of the altitudes (0 - 200 km) or to have air pressure input parameter, which I can type. For example pressure for 152 km is $4.98\times10^{-7} kPa$ as mentioned here.
Calculate required power.
Calculation can be done for static case, like helicopter which is staying on the ground or moving up very slowly like 1 m/s.

I found this one which is good enough for me, but I am not sure if it is doing good calculations for high altitude (50-100km) and I can trust it. Below is the screenshot from it. I would be more confident, if I would be able to type air pressure, but not altitude.

P.S. I do not want to dispute if it make sense or no to use propeller at high altitudes. I just want to know if there is software which can do this calculation. I will do calculation and based on the calculation will decide if it make sense or not. Please do not put comments about propeller inefficiency at high altitude.

Propellers are not effective at high altitudes, why do you want to consider it? Might be something you need to use a Matlab or Simulink model for.

At that altitude the energy equation in Navier-Stokes cannot be decoupled from the momentum equations, which is an assumption commonly made otherwise. In other terms, the speed of sound at that altitude is so low that almost any propeller will be supersonic. So it is unlikely that an off-the-shelf software will suit your needs.

Do the prop manufacturers have any tools? These are 3 that I am familiar with for small planes: MT-propeller.com, Hartzellprop.com, Mccauley.txtav.com  Are you only interested in helicopter blades?

Helicopter blades may not be too effective at high altitude, but they have managed to land on Mt Everest, both at the base camp at 18,000 feet and the summit at 29,000 ft. https://qz.com/391598/why-helicopters-havent-evacuated-everyone-from-mount-everest-yet/

@AEheresupportsMonica On high altitude it will be supersonic, but air density is low and maybe it is not bad, that propeller is supersonic. Actually, I do not want to dispute if it make sense or not. I just want to know if there is software which can do this.

@CrossRoads Yes, I am interested only in helicopters. Like something vertically going up very slowly or hanging at the same altitude with the propeller usage.

I am not disputing whether it is good or bad, that is obvious, I am just saying that this is vastly out of the scope of typical propeller design software. None of the propeller programs I have worked with deal with high mach numbers reliably.

Actually, it is even weirder. TIL that the speed of sound mostly increases in the ionosphere beyond 100km.

@AEheresupportsMonica ok, thank. I understand.


text:
Why is turbine inlet temperature called "TET"?
I assume that at some point giggling engineering students caused their instructor to change "turbine inlet temperature" from TIT to TET, but I wonder if anyone knows the real reason and history? Perhaps adapted from another language?

The temperature in jet engine turbines is usually measured in one (or more) of these places:

Behind the combustion chamber at the turbine inlet: Turbine Inlet Temperature (TIT)
Between low and high pressure turbine: Interstage Turbine Temperature (ITT)
Behind the last turbine stage: EGT (Exhaust Gas Temperature) or TOT (Turbine Outlet Temperature)

As far as I know, TET is not used as an acronym for Turbine Inlet Temperature, where TIT is used.
There are however two different definitions for TET:

In gas turbines for power plants, TET stands for Turbine Entry Temperature and is defined in ISO 11086:1996 (Gas Turbines - Vocabulary).

It is very important for gas turbine calculations how the temperatures
in the hot part of the gas turbine are defined:

TIT - Turbine inlet temperature is defined as the temperature that would occur before the nozzle guide vanes, if all cooling air was
mixed into the flue gases at that point.
TRIT - Turbine rotor inlet temperature is the temperature before the first rotor stage, i.e. right before the work extraction
begins.
TET - Turbine entry temperature is the actual temperature before the nozzle guide vanes.

(Gas Turbine Cooling Modeling - Thermodynamic Analysis and Cycle Simulations by Kristin Jordal)

TET is also sometimes defined as Turbine Exit Temperature, e.g. in this paper (also for power plant gas turbines) or in this patent (for a jet engine):

We have found that the turbine inlet temperature (TIT) or turbine exit temperature (TET) are viable parameters for indicating stall [...]

To avoid confusion, always check the glossary of the document when encountering TET. If there is no definition, it might be difficult to tell what the author meant.

Ahhh, excellent post. My confusion is from a 1970s article by the Olympus team that refers to TET without defining it - when I googled the term the resulting article was on TIT. I did not notice the fine print.

The turbine inlet temperature is pretty much fixed, unless you have a flame-out, since the combustion temperature depends mainly on chemistry, not aerodynamics.  On the other hand the exit temperature depends strongly on the mass flow through the turbine and the power it is producing, so it is a much more useful measure of "what the engine is doing" (not to mention that it is lower than the inlet temperature, and therefore easier to measure).

Please note that the TIT cannot be measured as it is generally too high for cooled turbine engines. Also, the SOT is sometimes referenced, the Stator Outlet Temperature, i.e. the temperature behind the nozzle guide vanes.


text:
Why is the IATA Airline Accounting Code abbreviated as PAX?
I'm dealing with some configuration files used in a software system. There's a single configuration file for each airline, e.g. like for Cathay, below:
"IATA": "CX"
"PAX": "160",
...

My understanding is that PAX is used to indicate a passenger count, is that understanding incorrect?
I figured out that the PAX is referring to the IATA Accounting Code for the airline:

But why is IATA calling this 'ACCOUNTING CODE(PAX)', when apparently PAX is used to refer to 'passengers'? Is it because this is specifically the accounting code for passenger transactions?

Is it a passenger capacity for a given configuration, rather than the count for a particular flight?

Thanks @Ralph J, but no, there's a single configuration file for the airline - sorry, I've updated the question to make this clear. I've figured out that the 'PAX' is the accounting code, so my remaining question now really is, "is it the accounting code specific  to passenger transactions"

It is called PAX because this is the accounting code for passenger operations. IATA has two kinds of these codes called Accounting Code for passenger operations and Prefix Code for cargo operations.

Accounting or Prefix codes
Airline accounting codes and airline prefixes are essential for the identification of passenger and cargo traffic documents, processing of passenger accounting transactions, cargo transactions and other commercial/traffic purposes.

(iata.org)
An airline can have both codes if they are operating both passenger and cargo flights, as seen in the following list of requirements to obtain such codes:

For a 3 Numeric Accounting Code (Passenger Operations)

Valid Air Operating Certificate (AOC).
Certificate of incorporation / Company Registration, with shareholders name.
Confirmation issued by the data aggregator (i.e. OAG, Innovata)

(only if a scheduled airline)

One of the following criteria must be meet;

Passenger Bilateral Interline Agreement with an IATA code holding airline
Confirmation from BSP (IATA Billing and Settlement Plan)/ARC (Airline Reporting Corporation)

For a 3 Numeric Airline Prefix Code (Cargo Operations)

Valid Air Operating Certificate (AOC).
Certificate of incorporation / Company Registration, with shareholder names.
Satisfy requirements to publish schedules in airline guide publications (only if a scheduled airline)
One of the following criteria must be met;

Cargo Bilateral Interline Agreement with an IATA code holding airline.
Confirmation from CASS (IATA Cargo Accounts Settlement System)
Letter of confirmation from a Freight Forwarder that will be issuing AWBs on your behalf

If applying for both codes, both requirements for each code will need to be met.

(portal.iata.org)
In your example, Cathay Pacific has both an Accounting Code and a Prefix Code of 160 because they operate both passenger and cargo flights.


text:
Is the T-38 wing strong enough to carry any weapons?
First, let me just clarify that I'm aware the T-38 doesn't have the necessary hardware to actually support firing weapons -- it doesn't have a fire control radar, for one. In any case, I'm still curious:
Question: What are the main differences between the wing for the T-38 and F-5? Is the T-38 wing strong enough to carry weapons, such as a couple AIM-7's?
From an answer at Quora it is claimed the wing is stronger on the F-5 to support hard points for weapons. However, is this true? There are no references on the Quora answer. I'd love to see some kind of decent reference, details about the wing, loading capacity, structure, diagrams?
These are pretty old aircraft and I would have thought the details for the wings are publicly available, but perhaps, they simply are not? If that is the answer, I'll accept that. Having good sources for details about wings might also aid those developing accurate simulators, like DCS, etc. E.g. how much does the wing flex under a certain load and when does it break, on the F-5? Is this publicly available? Not trying to roll many questions into one here, just trying to justify the question at all.
From the following diagrams it seems like the F-5 has a leading edge extension to the wing, but it isn't possible (at least for me) to say anything else about the wing profile or its strength.

While this does not relate to the wing, the AT-38B is/was weapons capable, on a centerline pylon. https://www.nationalmuseum.af.mil/Visit/Museum-Exhibits/Fact-Sheets/Display/Article/196733/northrop-at-38b-talon/

The T-38's wing is strong enough to carry weapons without a significant weight increase.
Not because of any special design for that.
It's just that any jet's wing is strong enough to carry an additional load mid-span, because that doesn't add to the spanwise load.
Structurally, you can think of an aircraft as resting on its wings, placed on a very soft foam bed. Hanging weight in the middle of the wings or at the wingtips doesn't just not increase the stress, it actually decreases some of the stresses in the wing.
Hardpoints still have to be built into the wing, though. You can't just attach the missiles to the lower surface with suction pads or adhesive tape. And there is some possibility of destructive flutter modes if the job isn't done right.
But nothing about the T-38's wing prevents it from being done right, at minimal weight increase. Some engineering and testing to be done to check the wing's behavior. In other words, it's easy to build an armed variant of the T-38, and takes some effort to add missiles to an already-built one.

The wings are strong enough for a munition, because they hold the weight of the whole aircraft via the landing gear.
Adding a few hundred pounds of missile, or a 500 lb bomb on each side, would not be an issue.
Of course the hardpoints and circuitry would need to be built in to the wing. But the actual wing would be plenty strong enough.

Even if the landing gears aren't there the wings of all aircraft MUST be capable of holding the weight of the whole aircraft in flight. The point of the average center of lift on the wings is the least stressful part to add weight in flight

I would have thought the point of maximum bending moment, I.e. the wingtip, would be the place to reduce bending stress.

There are plenty of things that do make a difference and "strength" isn't really enough of a discriminator. In particular, adding things to wings can cause divergent aerodynamic oscillation (aka "flutter"). Reaction loads (e.g. from release / jettison) are local strength and fatigue issues, not always at the wing-level.
Edit: It isn't easy to work out whether flutter is an issue for any given configuration. That usually needs wind-tunnel / CFD level analysis, followed by instrumented flight test. The specific weapon (or other store - e.g. fuel tanks, cargo pod), rack configuration and location on the wing make a lot of difference. Adding stiffness (e.g. strengthening for local reaction loads) can make things worse or better. The only thing you can safely say before that analysis and test program is "flutter might be a problem, and if it is, the wings might rip off".

This is a valid observation, but it doesn't answer the question. Would the T-38 wings suffer from flutter?

The T-38 wings might do - added some edits.


text:
How can the F-16 remain stable when there is a loss of hydraulic power?
Edit for justification:
This question is different from If the EPU (Emergency Power Unit) on a modern fighter jet fails, will the aircraft drop out of the sky? for the following reasons:
The question in If the EPU (Emergency Power Unit) on a modern fighter jet fails, will the aircraft drop out of the sky? asks if an aircraft drops out of the sky if the EPU (Emergency Power Unit) fails, for a generic aircraft. The accepted answer only briefly touches on the F-16, and certainly not in a way to answer this question. This question is specifically about an aircraft with RSS (Relaxed Static Stability), and how this relates to loss of hydraulics and power.
Question:
The F-16 has Relaxed Static Stability (RSS) to enable a high degree of maneuverability.
This causes the aircraft to be inherently unstable and RSS is corrected for by the on-board computer in real time, as part of the fly-by-wire system.
In the event of loss of hydraulic power, the ailerons cannot be operated, the on-board computer/avionics will also fail, if there is no power. The EPU (Emergency Power Unit) will re-establish hydraulic and electrical power, but this doesn't happen instantaneously. It takes some seconds.
During this critical window, what allows the F-16 to remain in stable flight in the context of RSS?
Reading this PDF it seems that the F-16 can be unresponsive to pilot input, yet remain in stable flight.
My question is, how is this achieved? How is it possible?
My own reasoning:
Either the F-16 is not as inherently unstable as I'm given the impression it is, or, there is enough hydraulic power and electrical power left in the interim between power from main hydraulics to switching to the EPU to allow the fly-by-wire system to keep the aircraft stable.

Make a scale model of an F-16 and throw it.  It is designed for supersonic flight, and may only need computer help under certain conditions. A few seconds in straight and level subsonic flight (most of the time) should be enough time.  If your F16 is too unstable, see what can be done to make it more stable if you are thinking of using it for passenger service (without computers).

Possible duplicate of If the EPU (Emergency Power Unit) on a modern fighter jet fails, will the aircraft drop out of the sky?

The battery would provide power to critical things like the FBW computers, and a pressurized hydraulic system bleeds down, rather than going to zero instantly. Perhaps this combination is enough to keep the aircraft from departing controlled flight while the EPU starts.

@Robert DiGiovanni I've heard this before, and I don't understand its relevance. The center of gravity highly influences stability on any aircraft. What exactly is the center of gravity on the F-16? Also, I'm not convinced that a tiny F-16 model exhibits the same aerodynamic properties as a full scale model. Aerodynamic forces change as a function of speed and air density, the model might exhibit stable flight, while the full scale model may not. I would need to see a reference for this -- that a scale model F-16 can be used to exactly simulate a real F-16.

@Ralph J Very nice comment. Would you consider putting that up as an answer?

@fooot I've edited my question to explain how this question is different.

@ AlphaCentauri It is more than CG.  At 25 knots CG is the cat and aerodynamic stability is the mouse.  At 250 knots aerodynamic stability is an elephant.  "Tiny models" usually scale up very well.  The F-16 does have a big nose, which, in addition to housing sensors, seems to cleverly give it enough directional instability to make it well, an F-16. (others use canards).

The F-16 has an APU as well, right? By the time the turbine, APU & EPU have failed, the plane should've been back at the ground anyway.

@Mast The F-16 doesn't have an APU.

@Mast I think you misunderstand the context of the question, it takes some time for the emergency systems of the F-16 to "kick in", and in this window (however small), is the aircraft stable?

You're correct, the F-16 is indeed one of the few fighter aircraft without APU. It has a JFS and EPU, no APU.

As I understand it (I'm neither an F-16 pilot nor an F-16 mechanic), Relaxed Static Stability doesn't mean the aircraft is unstable, just that it's less stable than the long-established standard.
To put it another way, if you build a free flight model airplane scaled from an F-16, you'll have to put the center of mass significantly further forward than its location in the full size, piloted F-16, in order for the model to have static stability.  The same is true of many radio control models intended to be flown by an experience model pilot -- they're what's call "neutrally stable".  The primary characteristic here is that these models will "go where you point them" and require that you "fly them all the time" -- unlike a trainer, or many/most scale models of piloted aircraft, you can't just set the throttle to cruise and take your eyes off the airplane, and expect to find it in a predictable location a minute later.
The same is (mostly) true of the F-16, in that, in most flight regimes, it's stable enough that as long as a violent maneuver wasn't in process when the flight computer restarts, the aircraft won't be badly out of shape by the time the computer returns to full function.  Back in the 1980s, however, it wasn't unheard of for a pilot to have to eject due to a fly-by-wire system failure; my parents lived near Hill AFB and would hear by local rumor mill and newspaper of "another F-16 crash" every so often.
Bottom line (again, based on my understanding as an "interested bystander") is that the F-16 is just about stable enough that it can remain recoverable through a control system restart, if it was in a steady state flight condition beforehand.

+1 for your answer. You can set up a model to be "staticly unstable (in pitch)"  as long as it is still DIRECTIONALLY stable (aerodynamic nuetral point is usually well behind the CG). The elevator is trimmed down. These models have an interesting property of "altitude or speed stability" because the increasing aerodynamic pitch down is cancelled by increasing lift trying to make the plane climb with increasing speed.  But if you go too slow, the cat will be waiting.

@RobertDiGiovanni But if you go too slow, the cat will be waiting Which is probably why most of the Hill AFB crashes I recall (from the period my parents lived in that area) were on landing or takeoff.  Lose fly-by-wire at 50 feet at 20 kt above stall, and you've got a problem...


text:
What is the difference between a weapons training aircraft and an actual combat aircraft?
From the Wikipedia page on the Northrop T-38 Talon:

Most T-38s built were of the T-38A variant, but the USAF also had a
  small number of aircraft converted for weapons training (designated
  AT-38B), which were fitted with a gunsight and could carry a gunpod,
  rockets, or bombs on a centerline pylon. In 2015, 504 T-38s were still
  operational with the USAF, with many more in operation around the
  world.

What, if any, is the difference between these weapons training capable T-38B and an actual combat aircraft? Is there anything missing (intentionally or otherwise) on a T-38B that would render it ineffective for actual combat, or is this term "weapons training" merely a term used to describe a trainer aircraft? A trainer, due to its age and ineffectiveness against modern aircraft?
Could it be fair to compare some variants of the F-5 against the T-38B? I'd be interested to know the difference, since the F-5 is undoubtedly an actual combat aircraft and not a trainer.

A trainer for the military, just like civilians, is slow, cheap to buy, cheap to repair, cheap to operate, and easy to fly. Adding weapons systems doesn't change any of that. Actual combat aircraft will be radically different on all counts.

The F5 may have been planned to be suitable as a combat aircraft, but I don’t think it ever made the cut or was actually deployed operationally.  The only ones I know af were used as aggressors in advanced training.

@MichaelHall, that might be the case with the US ones, but they were sold to many countries and they were used in actual combat in some of them (at least in Iran).

@jan hudec, good point.  I am obviously too Americacentric!

How about an aircraft fitted with sensors for weapons deployment but no actual weapons? This could be a weapons trainer.  I would imagine simulators are used for this purpose now.


text:
What astronauts and/or pilots had their "own" T-38 for transportation and practice?
It appears that the T-38 was used as a means of transportation for certain personnel. Astronauts, and certain pilots? It appears it was also used for training in some cases.
From some articles regarding astronaut training, it seems that some of them had their "own" T-38, that they could more or less use arbitrarily for transportation and training.
I'm curious what pilots and/or astronauts had access to T-38's, and to what degree they had their "own" plane. What were the limitations surrounding their use? Could an astronaut of the Apollo era, take the T-38 for a recreational trip to some other airport?
I'm thinking of articles such as this:

Yes, the jets were used for transportation to training sites.

and this

After the announcement pilots could fly the F-117 during daytime and no longer needed to be associated with the A-7, flying the T-38 supersonic trainer for travel and training instead.

No pilot or astronaut has "their own aircraft". Not in any unit I've ever seen.
Their name might be painted on the side of one, but they fly whatever the maintenance shop gives them for that day and mission.
Transportation? Sure. "Major Snuffy has to go to Houston for some training on the FooBar hardware. Ralph, take him, and go back on Thursday to pick him up."
Of course, this counts towards flight hours, mission and route planning, etc, etc.
"Borrow" a jet"? When I was stationed at Griffiss AFB NY in the late 70's, we sometimes had a pilot go for a weekend cross country. Leave Thursday or Friday afternoon, come back Sunday afternoon. Off to Frostbite Falls, MN Regional airport, to visit Mummy and Daddy for a couple of days. And we were loading golf clubs, skis, whatever, in the underwing travel pod.

Having kept my plane at Reno for a good many years, at an FBO that also serviced transient military, I can say that I certainly saw more fighter jets (and sometimes transports like the  C5) on the ramp on weekends than during the week.

Strategic Air Command had program for copilots to fly T37 trainers so they could get more fly hours at less expense then flying B52s or KC135s. Many pilots would take overnight bag and a set of golf clubs and fly to other SAC bases to visit friends and play a round of golf. We often joked that the golf course was built as soon as the runway was finished at a new base.

Over the years NASA has maintained a fairly sizable fleet of T-38's for use by the astronauts and the T-38 has been widely used by NASA as a training and proficiency aircraft as well as a chase plane. Astronauts are generally required to log a fair bit of time monthly to stay current.

Anyone who didn't fly a T-38 before they got to NASA learned to fly it
once they joined the astronaut corps. Basic astronaut training
includes T-38 courses, and mission specialists, who do not sit at the
controls of a space shuttle, have to record four hours a month at the
stick of a T-38. Commanders and pilots are required to fly the T-38
for 15 hours a month to keep up their proficiency.

In the early days the jets were used for hopping around the country since the Saturn V was built by many sub-contractors as was the case of the fatal NASA 901 Flight

Over the course of several months of training, See had flown 25 times
and Bassett seven times to St. Louis, in order to visit the McDonnell
Aircraft Corp., where their Gemini IX spacecraft was being built. The
flight from Ellington Field to Lambert Field took approximately 90
minutes and on the morning of 28 February 1966 See and Bassett,
together with Stafford and Cernan, were headed to St. Louis for ten
days of intensive rendezvous training on the Gemini simulator. They
would also have the opportunity to view their spacecraft as it
approached completion on the McDonnell production line.

Its reported that Michael Collins (Apollo 11) flew his T-38 alone often, to "commute" however this was between two NASA facilities

Collins spent months training for the delicate particulars of the
Apollo 11 mission. He commuted between NASA centers in Houston and
Cape Canaveral on a T-38, a slinky two-seater jet, usually alone.

But... In 1994 they got into some trouble, and it appears they were flying them just to "go places"

Astronauts at the Johnson Space Center in Houston have flown
two-seater supersonic jets to Colorado Springs on weekends during ski
season as well as to New Orleans and Fort Lauderdale, Fla., according
to NASA's inspector general.
While the astronauts said they were fulfilling the flight time
required of them each month, some lawmakers criticized the flights to
resort cities. Each costs about $2,000 an hour.

...and apparently it happens every once in a while

This is not the first time that astronaut flights on T-38's have been
criticized. From 1986 to 1990 there were more than 10 incidents
involving T-38's. In one, in May 1989, a Pan American World Airways
jetliner reported a "near midair collision" with a T-38 at Dulles
International Airport in Virginia.

The article goes on to discuss that the flights for proficiency were "loosely" monitored and NASA cared more about them getting their time in than the destination which appears to have lead to some not-so-sanctioned use of the aircraft.
On a bit of a side note this is a fairly common thing in aviation. Since the FAA required civilians to keep up certain currencies flight are routinely conducted for the purposes of maintaining currency instead of going somewhere specific, often pilots will simply fly to get lunch somewhere...

While stationed at NAS Glenview in 1970, I had Hangar One watch duty late one summer night.  I got a call to park an arriving NASA T-38 on the flight line.  It was Gene Cernan by himself that exited the aircraft.  I walked with him to Flight Operations, all business, no small talk.  He had yet to walk on the moon.  Chicago was his home town and I am sure this was not his only trip.  Buzz Aldrin also showed up there once but I never saw him, only the T-38.  Somebody in the VA-209 squadron spray painted the Blackawk insignia on the landing gear and heard Aldrin was furious, demanding heads to roll.


text:
What lights to use for a high-altitude weather balloon?
I am designing a high-altitude weather balloon for a college project. The balloon may fly at night, which means that, per FAA regulations, I need a light that is visible for 5 miles.
Does anyone know how to calculate this? Or knows some cheap and lightweight LED lights that work for this application?

Search on AircraftSpruce.com for anti-collision lights. They aren’t cheap, starting around $500. Since it is just a project, you won’t need a TSO version. This one is lightweight and says  "Exceeding all TSO intensity requirements" https://www.aircraftspruce.com/catalog/elpages/aveoredbaronmini.php?clickkey=424794

hmmm $500 is our entire budget haha, but this has given me a good place to start! Thank you


text:
How are military jets given official names?
How is a military jet given a nickname? Does the manufacturer name the plane? For example, did Lockheed Martin name the Raptor (F-22) and Lightning II (F-35)?

I wonder if this can be (sometimes at least) the name of the project used by the design team and the customer. Every large project, especially in US companies, is given a name, so that the customer remains anonymous, and the product the company works on cannot be guessed by employees not working under the non-disclosure agreement signed by parties. Often the codename used for many months remains after the project has been made public and the product delivered.

The original name for the F22 during it's development was the Lightning II. This was then changed to Superstar, then Rapier and finally Raptor.

Typically for modern US aircraft, since the military pays the contractor for the aircraft's development, so they are paying for it, and get to name it. This article says the USAF named the F-35 as the "Lightning II". However, the reality is much more likely, the F-35 Joint Program Office (the JPO), named the aircraft, given it international status and being a joint aircraft, and the announcement was made by the USAF. The JPO, being a joint office, always has a Program Executive Officer (PEO), and a Deputy, from both the USAF and USN (alternating positions). The F-22 was likely named by the USAF F-22 project office, which was based at Wright-Patterson Air Force Base, Dayton, Ohio. See here.
However, this isn't always the case, at least historically. For example, the Lockheed Orion & Hercules,  (and the Constellation) follow a tradition of Lockheed of naming their aircraft after celestial objects, stated here and here. The A-12 was also named by flight crews as the Cygnus (swan), another constellation, to follow this pattern. So, some US military aircraft, in the past, have been named by the manufacturer.
As another example, the F-111 is believed to be the only US aircraft to go through its service career without being officially named. On its retirement, the USAF designated it the "Aardvark". While the name was made official by the USAF, it came from the term the crews used for it.

Its American crew called the F-111 the Aardvark. It was a good name. Like the South African aardvark, the F-111 was a solitary night hunter. Like the aardvark, it rooted in the dirt, guided by excellent senses. And like the aardvark, it had very long range. For much the same reasons, Australians called it the Pig.

So, while in the past, sometimes the manufacturer named the aircraft, sometimes the crews, it would seem, today, the US government, through their military force, chose the name.

Ah yes......airplane names.  Official ‘names’ for aircraft come from various sources for a variety of reasons.  OEM engineers usually hold this with a great deal of disdain, finding it extremely dorky to call such a design a ‘Fighting Falcon’ or a ‘Hornet’ and generally prefer to call them by internal company designations eg Lockheed Martin Model 632 is better known to the public as an F-22 Raptor, etc.  Some names occasionally come from within the OEM like the YF-23, which received the nickname of ‘Black Widow II’ both in honor of Northrop’s earlier P-61 Black Widow and the arachnid shaped radar returns it produced earlier on during development.
Military program offices usually create official names, some deliberately for political or otherwise reasons.  An F-35 is called the Lightning II in honor of both the US Lockheed P-38 Lightning and the UK English Electric Lightning, the latter a fitting tribute since the UK was the biggest contributor partner nation, both financially or otherwise, on the JSF project.  Another example is the F-14, given the name ‘Tomcat’ both in honor of the feline name heritage for Grumman’s long line of naval fighters and for Admiral Tom Connolly, who resisted McNamara’s efforts to accept the troubled F-111B as the Navy’s new fighter and lobbied for a new design.
These names occasionally do not stick; The USAF originally called the F-16 airplane the ‘Fighting Falcon’ but F-16 aircrews never liked the designation.  Instead they called the airplane the ‘Viper’, in reference to the fictional Viper starfighters in the TV show Battlestar Galactica.  The jet also was informally nicknamed ‘Electric Jet’ in reference to its then novel fly-by-wire flight control system and ‘Lawn Dart’, in reference to how numerous development F-16s augered in and crashed while engineers struggled to perfect said system.
Speaking of that, most aircraft names are created informally by aircrews.  Some are flattering like the SR-71’s ‘Lady in a Black Dress’ or ‘Habu’ after a venemous snake indigenous to Okinawa.  Some are not eg the F-105 Thunderchief is the ‘Lead Sled’ after it notoriously poor maneuverability, the A-7 is the SLUF or Short Little Ugly F*cker.  It’s also common in the civilian world.  An A-320 is often called ‘Scarebus’ - a play on Airbus, ‘Nintendo Jet’ and ‘Die by Wire’ - referencing the jets flight control system, ‘Sully’s Ark’ - referencing the Cactus 1549 crash on 1/15/09, etc.

Interesting historical note: Convair had a contest among its employees to submit names for the aircraft, the winner receiving a $50 prize. Judges chose the name “Peacemaker” and officially recommended the name to the Air Force. Religious groups objected, saying the only “Peacemaker” was Jesus, so the B-36 never received an official name. It was simply “B-36” officially. You can view the certificate here

If you don't add the "Turkey" for the F-14 and "Scooter" for the A-4 there will be no joy in Mudville. 8^D

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
Why was the F-117 retired so quickly?
Why was the F-117 retired after so few years in service (Approximately 25 years) while other military aircraft are in service for many decades? Many of the 60 built should still be air-worthy.
For example, the F-15, F-16, and F-18 models have been kept in service for 40 years.

Several reasons can be found for its early retirement:

the aircraft was instantly obsolete after one was shot down over Yugoslavia by a 30 year old SAM system
Maintenance was pretty expensive and difficult (and according to some involved large quantities of highly toxic chemicals that are still causing health problems for the people involved)
Few military reasons to keep it in the existing threat environment. An F/A-18 is cheaper to operate than an F-117 for bombing missions against insurgents and terrorists.
Politics. Retiring the F-117 could have been intended as a step towards asking for funding for more F-22s, claiming that the USAF was now without a tactical stealth aircraft for the ground attack mission (the F-22 at the time was envisioned as a multi role aircraft, having a secondary ground attack function like the F-15 and F-16).
The F-15 and F-16 have been kept in service through extensive replacement and upgrade programs for older models. There never was an upgraded F-117 proposed or built. The F/A-18 E/F are effectively a completely new aircraft and shouldn't be considered the same type as the older A/B.

It was less the aircraft itself that became obsolete than the extremely static mission planning which sent the F-117 on the same route, day after day. All the Serbs had to do was to point their missile at the right spot and fire it at the right time once they had learned the schedule.

@PeterKämpf true, but under the original idea that missile never would have been able to get a lock on the aircraft. That's where the obsolescent technology failed it (and indeed, the planning and flight crew ignored SOP by flying the same route day after day, making themselves predictable).

Get close enough and every stealth aircraft becomes visible. Luftwaffe pilots who participated in exercises with F-117s were regularly briefed not to disclose how much of the F-117 could be detected by their aircraft's sensors. Just this much: They were not completely invisible. A decent missile will get a lock on a low-flying F-117 that flies directly overhead.

@PeterKämpf yes, but not at the distance and using the systems employed for the shootdown in Yugoslavia. There it was triangulation using multiple radars at a distance that should not have led to detection, leading to a visual fix on the aircraft and eventual optical tracking of the missile to an infra red lock on the engine exhaust (which was also deemed to be next to impossible, though the distance may have been short enough at that stage to make it within the design parameters of the aircraft).

Actually the shooting of the F-117, from interview of the Serb commanding officer of the battery, relied only on radar-led interception. Flying to close, the F117 was detectable by the low band radar. Without jamming support nor radar receiver warning, it could not avoid the lock of the fire control radar. With a straight flight path and without warning, the F 117 could not escape the missile

@totalMongot given that the missile used was one with IR terminal homing and a backup manual mode, that may be true for the detection and tracking phase, but not for the terminal phase (and given that the shootdown happened at night, the optical mode would be pretty much useless).

@jwenting Sorry could you please detail your comment? I don't understand entirely the point you want to make

@totalMongot because of the conditions during the shootdown (dark night) visual tracking wouldn't work as the aircraft would be invisible to the naked eye.

@jwenting Ok yes, so that backs up the fact that the battery relied only on radar-led interception